code: def _flat_set(x):
      if x is None:
          return set()
      elif isinstance(x, set):
          return x
      elif not isinstance(x, (list, set)):
          x = [x]
      return set(x)
  
imports: from __future__ import annotations
  import math
  import numbers
  import uuid
  from enum import Enum
  from dask import config, core, utils
  from dask.core import flatten, get_dependencies, ishashable, istask, reverse_dict, subs, toposort
label_desc: Use image node_id 4 for calling a global function with example usage: _flat_set(x) and returns: set, set, x